Electric-circuit safety lock



March 4, 1930. A. B. ESSELTINE ELECTRIC CIRCUJII SAFETY LOCK Filed Dec. 31, 1927 Patented Mar. 4, 1930 UNITED STATES PATENT G UODIEAN MANUFAC- lif OF ILLINOIS ELECTRIC-CIRCUIT SAFETY LDCK Application filed December 31, 1927. Serial No. 243,658.

My invention relates to electric circuits involving removable circuit connections such as overload fuses and has for its general object the provision of means whereby a removable circuit connection such as a fuse cannot be removed or replaced while the circuit is otherwise closed, so that the danger involved in removal or replacement of the circuit connection while the circuit is otherwise closed is ebviated, the invention having particular reference to safety in underground mining where explosive gases are often encountered.

The invention will be more readily under stood by reference to the accompanying dravw ings, in which:

Figure 1 is a front elevation of electric circuit means embodying my invention with parts broken awayand in section;

Figure 2 is an end elevation of the same from the line 22 of Figure l and with parts broken away and in section;

Figure 3 is a partial view from the line 83 of Figure 1.

Like characters of reference indicate like parts in the several views.

Referring to the drawing, 1 designates a casing enclosing therein an electric switch including stationary contacts 2 and movable contacts 3 secured upon a pivoted shaft- 4i for angular movement into and out of engagement with the contacts 2 The shaft l extends outwardly of the casing with both ends thereof, and an operating handle 5 is secured on one of the shaft ends for the manual operation thereof to open and close the switch.

Mounted in fixed relation with the casing 1 and disposed upwardly thereof adjacent one end of the same is an enclosed electric fuse mounting 6 provided with an end opening for o the insertion and removal of a suitable electric fuse 7 therein. The fuse mounting 6 and the fuse 7 are of a well known construction and require no further description except to note that the fuse is locked in the fuse m0unting against accidental removal by means of a semicircular internally grooved formation 8 on the fuse mounting which is engaged and disengaged with a semicircular flange 9 on the adjacent end of the fuse 7 by angular movement of the fuse when in the mountin See Figure 8. b

Mounted for longitudinal movement in a board bracket 11 on the switch casing 1 is a vertically disposed red 12 the upper end of which is flattened and adapted tr move over the end ope r the nuiunting 6 and the end of the fuse herein to 156-1; the fuse against removal in the mounting. A crank member 18 seen on the end of the. shaft l opposite that en rob the handle 5 is secured and underlyin he rod 12, and a corn necting link has .7 ends nivotally connected respectively with the oiiter end of the crank member 13 and the lewer-end of the rod 12 whereby the rod 12 is actuated vertically with pivotal movement of the shaft 4 the arrangement sing such that when the switch is closed "t e upper end of the rod overlies the adjacen d o the fuse mounting and fuse therein and locks f n the mount-- ing, and when the swi h is open the rod 12 is in a lower position v i the upper end there-- of disposed below the end obeniug of the fuse mounting and fuse therein, thus unlocking the same I01 removal or replacement of the fuse.

The switch being circuit with the fuse mounting, the fuse can only be r moved or replaced when the circuit is in otherwise open condition wit i the result that arcing is prevented in the remo al or replacement of the fuse in the fuse mounting. While I have shown h rein and described one form of mv invention, I do not iish to be limited to the precise details of construction or arrangement of parts herein shown and described except as specifically limited in the appended claims.

I claim as my invention:

1. In a device of the character described, the combination with an enclosed electric switch including a movable switch member, of an enclosed electric fuse mounting provided with an end opening for the insertion and removal of an electric fuse therein, and means operated by said switch member including a locking member movable over said end opening to prevent removal of a fuse in said mounting when said switch member is moved to closed circuit position.

2. In a device of the character described, the combination with an enclosed electric switch including an angularly movable switch member, of an electric circuit connection mounting, a locking member niova'ble into and out of position to prevent remova-l-ofan electric circuit connection on said mounting,

and connecting link andcrank means for op erating said locking member into and out of said position with opposite movements of said switch member.

3. In a device of the cli a'raictiei" described, the combination with an enclosed electric switch including an anguia'rly' nibvable and ate of Illinois, this 28th day of December, A. D. 1927. v

ALFRED B. ES'SELTINE;

Signed at Chicago, in the county ofCook 

